In the field of outdoor lighting, one conventional approach to mounting a luminaire on a pole or building is to secure the housing on a generally horizontal cylindrical or tubular mast. The mast may fit into a sleeve or partial sleeve integral to the housing and be clamped to the housing by one or more clamps or U bolts bolted to the sleeve. For example, see U.S. Pat. No. 2,908,809 issued Oct. 13, 1959 to Beach et al. Another approach is to provide a frame or sleeve into which the mounting mast fits and using bolts or set screws to impinge against the mast and allow adjustment of the luminaire inclination. See U.S. Pat. No. 3,032,648 to Pfaff issued May 1, 1962.
The providing of external clamps or U bolts requires added parts and inventory. The partial sleeve of the mounting housing allows the housing to be cast or molded. With a full 360.degree. sleeve, the mounting section cannot be cast or molded integrally with the housing and must also be an add-on part as shown by the '648 patent.